This is a T31 Demolition tank and was an anti-fortification modification tested by the U.S. Army. It was armed with a 105mm howitzer (akin to the M4A3 105) and 2x 1833 7.2in revolving Rocket launchers on each side. I couldn't find decent sources on the 1833 launchers, but suspect they are similar to the 7.2in rockets used on the Sherman T40.
Developed on the M4A3 HVSS Chassis but with a much heavier turret, this vehicle would have been sluggish, but boasting huge firepower. The vehicle was developed in 1945, canceled due to the foreseeable end to the war and the introduction of the M26 with it's 90mm, able to complete the job nearly as well without a complete overhaul.